Chitosan membranes were modified with mouse epidermal growth factor (EGF) by a photochemical technique. Photochemical immobilization was performed via a two-step process, in which EGF was first reacted with a heterobifunctional cross-linker sulfo-SANPAH (sulfosuceinimidyl 6(4'-azido-2'-nitrophenyl-amino)hexanoate) and then immobilized on the chitosan membrane by UV irradiation. The success of immobilization process was checked by Fourier transform infrared attenuated total reflection spectroscopy and X-ray photoelectron spectroscopy. Atomic force microscopy was used to evaluate the surface topography. The mitogenic effect of the EGF-modified chitosan membrane was investigated using mouse fibroblasts (L929 cell line), and cell proliferation was investigated by MTT and crystal violet assays. The results obtained from cell culture experiments showed that immobilized EGF stimulated fibroblast growth on chitosan membranes, and a considerable difference in cell proliferation was detected on EGF-modified chitosan membranes. (c) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.